The present invention relates to an image recording apparatus for recording a color image on a photosensitive recording medium using mask members.
Conventionally, red, green and blue mask members are produced based on an imaging information so as to selectively allow particular light to pass therethrough. Each of the mask members is of a light shieldable monochromatic image indicative of particular color of the imaging information. Three mask members are successively placed on an identical area of the photosensitive recording medium for performing exposures at three times for obtaining a latent image thereon. In this connection a related art is described in U. S. Pat. Nos. 4,884,082 and 4,949,185.
According to these U.S. Patents, the mask members are successively fed to an exposure position in such a manner that the mask member is electrostatically suspended from a transparent endless belt such as PET belt, and the suspended mask member is superposed with the photosensitive recording medium for exposure.
More particularly, as shown in FIG. 1, the red, green and blue mask members are successively fed one by one through an inlet 126 into an exposure position with a mask imaging surface facing downwardly. For example, when the red mask member is inserted through the inlet 126, the red mask member is directed downwardly and reaches one end (left end in FIG. 1) of an endless belt 102 extending in a horizontal direction. The endless belt 102 is formed of a transparent material and is charged with electricity by a charger (not shown). Therefore, the red mask member is attracted to the endless belt 102 and is fed to an exact exposure position because of the running movement of the endless belt 102. When the mask member reaches the predetermined exposure position, movement of the endless belt 102 is stopped.
At a position immediately below the endless belt 102, a photosensitive recording medium 106 drawn out of a cartridge 104 is positioned in parallel with the endless belt 102. Therefore, exposure operation is performed when the mask member confronts an exposure area of the photosensitive recording medium 106. A lamp 108 for the light exposure is positioned above the endless belt 102, and a filter unit including red, green blue filters 110R, 110G and 110B is positioned between the lamp 108 and the endless belt 102. The filter unit is movable in a horizontal direction so that one of the filters can be selectively positioned immediately below the lamp 108.
First, the red filter 110R is brought to the position immediately below the lamp 108, and the lamp 108 and the filter unit are integrally moved from one end to another end of the endless belt 102 for a light scan. Therefore, red light is irradiated onto the photosensitive recording medium 106 through the red filter 110R, the transparent endless belt 102 and the red mask member. In this case, the light can transmit the transparent base sheet of the mask member. However, the light is shielded or blocked at the monochromatic mask image formed on the mask member. Accordingly, the photosensitive recording medium is formed with a latent image indicative of the red color.
Upon completion of this operation, the endless belt 102 is further moved so as to discharge the red mask member therefrom(rightwardly in FIG. 1). The red mask member separated from the endless belt 102 is moved upwardly along a mask feed path. The mask feed path is branched into upper buffer section 116a and a lower buffer section 116 at a junction 114 at which a gate 118 is provided for selectively delivering the mask member toward upper and lower buffer sections. The red mask member is provisionally stored in the upper buffer section 116.
While maintaining the photosensitive recording medium 106 at the exposure position, the green mask member is then fed through the inlet 126 toward the exposure position when the precedent red mask member is discharged therefrom. The green mask member reaches the exact exposure position in a manner similar to the red mask member. When the green mask member confronts the exposure zone of the photosensitive recording medium 106, the lamp 108 and the filter unit are again moved from one end to the other end of the endless belt 102 with the green filter 110G being positioned immediately below the lamp 108. Thus green light exposure is achieved with respect to the exposure zone of the medium 106. Upon completion of the green light exposure, the green mask member is discharged out of the exposure position by the movement of the endless belt 102 and is delivered into the lower buffer section 116b. Simultaneously, the blue mask member is transferred to the exposure position and blue light exposure is performed with the blue light scanning in using the blue filter 110B.
Because of the three times exposure at the identical area of the photosensitive recording medium 106, red, green and blue latent images are superposedly formed on the identical area. The photosensitive recording medium 106 is then fed to a developing unit and a subsequent zone of the medium is pulled out of the cartridge 104 and is brought to the exposure position in confrontation with the endless belt 102.
On the other hand, the blue mask member is discharged out of the exposure position, and enters the upper buffer section 116a. Further, the red mask member previously stored in the upper buffer 116a is fed out of the buffer 116a, and is again delivered to an upstream portion of the exposure position. The red mask member is again introduced into the exposure position by the movement of the endless belt 102 so as to start a next exposure operation.
Therefore, the mask members are circulated in a closed loop for obtaining desired numbers of the color output images. In this case, the pivotal position of the gate 118 is controlled in accordance with the storage states in the upper and lower buffer segments 116a and 116b. When the desired numbers of the exposures are completed, these mask members are discharged through an outlet 120.
In the image recording apparatus shown in FIG. 1, the mask image surface of the mask member must be superposed with the photosensitive recording medium 106. Further, when the mask image is provided at a laser printer, the mask image surface faces upwardly. If the laser printer is mounted on the image recording apparatus, the mask member is introduced to the exact exposure position with the mask image surface facing downwardly. In this connection, the mask member must be positioned above the photosensitive recording medium 106 and must be hangingly suspended. For the mask suspension, the endless belt 102 is required, and it must be electrostatically charged in order to attract the non imaging surface of the mask member thereto.
Accordingly, additional components are required such as a charger, and means for preventing the suspended mask member from being dropped from the endless belt such as a roller and holding pawls. Consequently, resultant device becomes complicated and costly. Furthermore, in spite of the disposition of the means for mask member drop preventing means, it would be almost impossible to perfectly prevent the mask member from falling down from the endless belt 102. Therefore, high reliability may not be attainable. To be more specific, the circumambient condition may affect the electrostatic attraction of the mask member to the endless belt 102. For example, if high ambient humidity is provided, the attraction force may be lowered.
Moreover, the production of the transparent endless belt may be costly, and coating may be required to the endless belt to impart resistivity against any injury. Such coating may also increase production cost.